Related papers: Bright X-ray flares from Sgr A*

Strong iron fluorescence at 6.4 keV and hard-X-ray emissions from giant molecular clouds in the Galactic center region have been interpreted as reflections of a past outburst of the Sgr A* supermassive black hole. Careful treatment of…

We first present a short overview of X-ray probes of the black hole region of active galaxies (AGN) and then concentrate on the X-ray search for supermassive black holes (SMBHs) in optically non-active galaxies. The first part focuses on…

We report the results of XMM-Newton observations of Sgr A*, the radiative counterpart of the massive black hole at the nucleus of our Galaxy, performed in the frame of the guaranteed time survey program of the Galactic Center region. The…

Illumination of dense gas in the Central Molecular Zone (CMZ) by powerful X-ray flares from Sgr A* leads to prominent structures in the reflected emission that can be observed long after the end of the flare. By studying this emission we…

The Galactic Center black hole Sagittarius A* is a variable NIR source that exhibits bright flux excursions called flares. The low-flux density turnover of the flux distribution is below the sensitivity of current single-aperture…

The extended X-ray emission observed in the direction of several molecular clouds in the central molecular zone of our Galaxy exhibits spectral and temporal properties consistent with the X-ray echo scenario. This concept postulates that…

Measurements of stellar orbits provide compelling evidence that the compact radio source Sagittarius A* at the Galactic Centre is a black hole four million times the mass of the Sun. With the exception of modest X-ray and infrared flares,…

Most stellar flares' soft X-ray lightcurves possess a `typical' morphology, which consists of a rapid rise followed by a slow exponential decay. However, a study of 216 of the brightest flares on 161 pre-main sequence stars, observed during…

Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We have analyzed a comprehensive submillimeter (including new observations simultaneous with…

The broad X-ray iron line, detected in many active galactic nuclei, is likely to be produced by fluorescence from the X-ray illuminated central parts of an accretion disc close to a supermassive black hole. The time-averaged shape of the…

The Galactic Center is the closest galactic nucleus that allows us to determine the multi-frequency behavior of the supermassive black hole counterpart Sagittarius A* in great detail. We put SgrA*, as a nucleus with weak activity, into the…

Recent observations from the Swift gamma-ray burst mission indicate that a fraction of gamma ray bursts are characterized by a canonical behaviour of the X-ray afterglows. We present an effective theory which allows us to account for X-ray…

The compact radio source at the center of our Galaxy, Sagittarius A* (Sgr A*), is the subject of intensive study as it provides a close-up view of an accreting supermassive black hole. Sgr A* provides us with a prototype of a low-luminosity…

Galactic X-ray emission is a manifestation of various high-energy phenomena and processes. The brightest X-ray sources are typically accretion-powered objects: active galactic nuclei and low- or high-mass X-ray binaries. Such objects with…

In 2019, Sgr A* - the supermassive black hole in the Galactic Center - underwent unprecedented flaring activity in the near infrared (NIR), brightening by up to a factor of 100 compared to quiescent values. Here we report ALMA observations…

The nature of the emission region around Sagittarius A* (Sgr A*), the supermassive black hole at the Galactic Center, remains under debate. A prediction of jet models is that a frequency-dependent shift in the position of the radio core…

The radiative counterpart of the supermassive black hole at the Galactic center (GC), Sgr A*, is subject to frequent flares visible simultaneously in X-rays and near-infrared (NIR). Often, enhanced radio variability from centimeter to…

We have performed monitoring observations of the flux density toward the Galactic center compact radio source, Sagittarius A* (Sgr A*), which is a supermassive black hole, from 1996 to 2005 using the Nobeyama Millimeter Array of the…

The Galactic center provides a unique astrophysical laboratory for us to study various astrophysical processes. In this paper, we review and outline the latest results from observations of Sgr~A$^*$ in terms of source structure and…

We discuss implications of a strong flare event observed in the Seyfert galaxy MCG-6-30-15 assuming that the emission is due to localized magnetic reconnection. We conduct detailed radiative transfer modeling of the reprocessed radiation…